The correct answer is option 'C' - The President.

Explanation:

The Constitution of India provides for a bicameral legislature at the central level, consisting of two houses - the Lok Sabha (House of the People) and the Rajya Sabha (Council of States). These two houses have distinct powers and functions, but in certain circumstances, they can come together in a joint session.

A joint session of the Lok Sabha and the Rajya Sabha is convened under specific circumstances, such as:

1. When a Bill has been passed by one house but is rejected or amended by the other house: In such a situation, if both houses cannot reach a consensus through a process of negotiation, the President may summon a joint session to resolve the deadlock. The joint session is called to consider and pass the Bill, and the decision is taken by a simple majority of the members present and voting.

2. When the President desires to address both houses: The President of India, as the head of the state, has the power to address both houses of Parliament assembled together. This may occur at the commencement of the first session after each general election, at the beginning of the first session of each year, or at any other time the President deems necessary.

The power to convene a joint session lies with the President, and they exercise this power on the advice of the Council of Ministers. The President acts as the constitutional head and guardian of the legislative process, ensuring the smooth functioning of Parliament.

It is important to note that the Speaker of the Lok Sabha and the Chairman of the Rajya Sabha do not have the authority to convene a joint session on their own. The decision to convene a joint session is ultimately made by the President, who acts on the advice of the government.

In conclusion, the President reserves the right to convene a joint session of the Lok Sabha and the Rajya Sabha under specific circumstances outlined in the Constitution of India.